Adding Distribution Servers

Distribution Servers are added by defining existing hosts as Distribution Servers. Any host with a Management Agent can be changed into a Distribution Server. Since the purpose of the Distribution Servers is to share the load, select the Distribution Server hosts so that they cover a relevant area. Other hosts need to be able to connect to the Distribution Servers, and the server hosts need space for cacheing the installation packages.

You can also define the maximum cache size and downlink bandwidth for each Distribution Server according to the host and network capacity.

To add Distribution Servers into the system, follow the steps below:

In the main menu, select Hosts → View hosts. In the host list, select the host that you want to define as a Distribution Server by clicking the hostname.

A new tab Distribution Server Settings is added for defining settings for the server.

Figure 7.4. The Distribution Server settings

Cache size

This defines the maximum cache size of the Distribution Server. The minimum value is 0, which effectively disables the caching. Never set a value exceeding the host disk space, otherwise the cache fills the disk.

Each Distribution Server caches the transferred files (installation packages) in /var/opt/ssh-mgmt/dist-cache. When the total amount of cached files rises over this limit, the least recently accessed files are deleted to reduce the cache size under the limit. This is not a hard limit: if all files are in use (accessed during the last minute), they are not deleted. If files accessed during the last hour are deleted, the Distribution Server logs a message recommending increasing the cache size.

Downlink bandwidth limit

To avoid saturating the network, each Distribution Server has a setting to limit the total bandwidth of downstream file transfers. The setting is in bytes per second.

The limit should be set above zero. The default of 100 million bytes per second is the recommended maximum value.

The settings can be changed using the Edit button. Proceed to define which hosts will connect to each Distribution Server, and then deploy the changes. The settings are not taken into use before the Distribution Server is deployed by selecting Hosts → Host Connectivity → Deploy Hierarchy → Deploy now.